The present invention relates to a novel device usable as an intraocular lens within the eye to correct visual loss which occurs, for example, after cataract removal.
The clouding of the eye's natural lens, located behind the iris, is generally known as a cataract. To prevent blindness the accepted medical procedure entails removal of the natural lens. After removal, the patient's vision must be corrected because of the loss of the lens. Correction of vision has been effected in different ways. The first method fits the patient with spectacles or glasses. However, this reduces peripheral vision by about 65% and magnifies objects seen by about one third. If cataract removal was performed in only one eye, which is often the case, double vision would result because of the magnification problem.
Employment of contact lenses represent a better solution, since objects are only magnified by 8-10% and the patient's field of vision remains about the same as before lens removal. However, contact lenses cannot be worn by 50-90% of cataract patients, since they are usually elderly.
The intraocular lens was first conceived by Ridley and implanted in an eye as early as 1949. Dislocation of the lens caused its discontinuance. Later designs included the Lieb lens described in U.S. Pat. No. 2,834,023, which described an anterior chamber lens having loops formed of a thin resilient rod. Corneal dystrophy, and therefore blindness, occured when the loops contact the endothelium on the inner surface of the cornea. The endothelium is a corneal cellular layer which may die upon touching and usually does not regenerate.
Later designs included posterior lenses such as the one described in U.S. Pat. to, Flom, No. 3,866,249. Difficulty of insertion of such lenses has precluded their use in most cases.
The most recent anterior chamber designs such as those described in U.S. Pat. No. 3,673,616 to Fedorov et al, and in the Binkhorst-Worst, C. D. "Twenty Years Experience With Pseudophakia: Some Thoughts on the Fixation of Intraocular Lenses, " presented at the First International Course on Pseudophekia, Netherlands, June 1974, include loops that pass through the pupils. The most frequent problem encountered is that intraocular lens incorporating later anterior chamber designs tend to dislocate with the opening and closing of the pupil. This has, to a certain extent, been controlled with dilating and constricting chemicals. The Binkhorst-Worst lenses include the design of an anterior hook engaging a posterior loop through an iridectomy opening. Thus, one end of the lens rides with the opening and closing of the sphincter and dilator muscles of the iris. Placement of this lens has proved difficult because the mating of hook and loop is posterior to the iris. Likewise, the Binkhorst-Worst lens having suture holes within the haptic of the lens poses the danger that the suture material will deteriorate with time and will cause a dislocation of the intraocular lens. The use of metal wire sutures has proved undesirable since the maneuvering and fixing of such sutures is difficult.